The present invention relates generally to oil filtering equipment and is particularly concerned with apparatus for filtering hot cooking oil or shortening from a cooking vat.
Cooking oils used in restaurants or large kitchens of other types of institution tend to become contaminated after a time with contaminants such as small food particles and moisture. Particulate matter in the oil will ultimately make the cooked food taste bad, and the oil must therefore be cleaned or replaced periodically. Cooking oil from commercial cooking vats is typically cleaned by filtering, which is time consuming and can also be hazardous, since the oil will still be very hot while it is being filtered. Existing filtering systems are typically gravity operated, and the oil must be very hot so that its viscosity is low enough for it to flow through the filter media. Personnel may be burnt or scalded if hot oil is splashed during filtering, and any spilt oil can present a slipping hazard if not cleaned up immediately.
Even when filtered periodically, cooking oil must still be replaced relatively frequently to produce optimum results. Thus, cooking oil represents a significant expense to the food service industry. Current research findings indicate that the more expensive, all liquid vegetable oils are the most healthy oils for use in cooking, and large kitchens will probably have to switch to using such oils exclusively in the near future. Typical filtering systems in use in the food service industry often only extend the cooking oil lifetime to around 7 days, as compared to one day if unfiltered. Thus, a cooking oil filtering apparatus which could significantly extend the useful lifetime of an edible oil would considerably reduce expenses in the food service industry.
Typical cooking oil filtering units require a great deal of cleaning and maintenance, often after each filtering operation, and must often be assembled in advance of each filtering operation. Thus, the filtering procedure is lengthy and complicated.
In U.S. Pat. No. 4,826,590 of Turman a cooking oil filtering system is described in which cooking oil from a series of vats is filtered and returned sequentially to the vats via a pre-filter and a set of secondary filters which remove a larger proportion of particles from the oil, increasing the usable lifetime of the oil up to about one month. However, this system is relatively large and may not be suitable for all kitchens.